Question

Calculate the energy released when isotope of carbon, 146c , decays by β− emission. the atomic mass of 146c is 14.003242 u , the atomic mass of 147n is 14.003074 u . assume that the neutrino has no mass.

Answer 1

The correct answer is: 156.49 keV (0.15649MeV)

Explanation:
Since 

E = mc^2

Where E = Energy = ?
m = mass = (14.003242 - 14.003074) amu = 1.68*10^-4amu

Also 1amu * c^2 = 931.5 MeV

Plug in the values in the equation:
E = (1.68*10^-4)*(931.5 MeV) = 0.15649 MeV = 156.49 keV